Increased broadband access worldwide has meant a rise in demand for online media services and this could have implications for a society that is living within environmental limits.

Researchers have analysed the potential future demand for downloaded data worldwide, such as social networking sites and on-demand TV programs, and the resulting energy usage.

The researchers estimate the overall demand to be 3,200 megabyte (MB) a day per person, totalling 2,570 exabytes per year by the world population in 2030.

Based on two independent sources of data, the researchers found the current energy demand for bandwidth to be four watt-hours per MB. They conclude that the average power required to support this activity would be 1,175 gigawatts at current levels of efficiency.

According to the researchers, a factor 60-performance improvement would be needed if infrastructure energy is to be provided by one percent of renewable energy capacity in 2030. By looking at historical trends in energy efficiency, they observed that this would be reached around 2021 if these trends continue.

The researchers also outlined strategies to reduce the overall demand for bandwidth if historical performance improvements are not maintained. Example strategies suggested include techniques to reduce 'digital waste' – data downloaded but not actually viewed – and the 'persuasive' design of web pages to encourage people to opt for less data-intense options.

New applications were examined that might require bandwidth capacity beyond their estimate, such as high-definition online viewing and internet radio.

This research suggests that in a future which is increasingly environmentally constrained, there is still a good chance that broadband connectivity can be provided equitably to the majority of the world, said Chris Preist, Reader in Sustainability and Computer Systems in the Department of Computer Science.

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